ahearn



(No Model.) 2 SheetsSl1eet 1.

T. AHEARN.

ELEGTRIG HEATER.

No. 483,124. Patented Sept. 27, 1892.

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2 Sheets Sheet 2.

(No Model.) T AHEARN ELECTRIC HEATER.

No. 483,124. Patented Sept. 27, 1892.

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UNITED STATES PATENT OFFICE THOMAS AHEARN, OF OTTAIVA, CANADA.

ELECTRIC HEATER.

SPECIFICATION forming part of Letters Patent No. 483,124, datedSeptember 27, 1892- (No model.)

To all whom it may concern.-

Be it known that I, THOMAS AHEARN, of the city of Ottawa,in the countyof Carleton and Province of Ontario, in the Dominion of Canada, haveinvented certain new and useful Improvements in Electric Heaters; and Ido hereby declare that the following is a full, clear, and exactdescription of the same, reference being had to the accompanying draw-IO ings, forming a part hereof.

My invention, which will be hereinafter fully set forth and claimed,relates to appliances for obtaining and utilizing heat from an electriccurrent.

Figure 1 is an elevation of my improved heater. Fig. 2 is a horizontalsection of the same on line 00 as, Fig. 1. Fig. 3 is a vertical sectionof the same on line y y, Fig. 2, showing the inner tube in elevation, apart being broken out to show the section. Fig. at is a top view of thesame. Fig. 5 shows a modification of the core. Fig.6 is averticalsection of a modification having an additional inner and outer casing.Figs. 7 and 8 are top view and horizontal section of anothermodification having additional radiating or air tubes, and Fig. 9 is avertical section of another modification.

Ais atube of a (preferably) good heat-conducting material, such as iron,shown of circular cross-section in the drawings, but which may be squareor polygonal, plain or corrugated, or of any other desired crosssection.Upon the outer surface of this are laid longitudinally and at shortdistancesapart strips of asbestus B, and upon these again strips of micaB, these latter being so-called non-combustible materials andnon-conductors of electricity. Upon these strips is wound a coil 0, ofWire or strips of refractory metal of low electric conductivity, such asGerman silver and the like, the terminals of which are connected withleads 0 and c, and each of these is passed through an insulator C, whichis afterward secured in the outer metallic casing. This resistance-coilis preferably wound in opposite directions to check induction.

D isthe outer casing, consisting of a metallic tube having the samelength as the inner tube A and large enough to allow a clear annularspace between its inner surface and that of the cored coil, and being ofsuch a shape in cross-section as to correspond with the outline of thelatter. The annular space thus formed is packed with powderedfire-clay,whit-ing, or other powdered non-conducting material F. Anasbestus packing-ring E is placed at each end, covering the space sofilled and the edges of the two tubes, and these rings are held in placeby a cover-E at each end provided with lugs 0, through which pass boltsE. The lower cover is provided with insulator-feet G, so as to raise itsufficiently off the floor to allow free access to a current of air toenter into and pass through the inner tube. This construction admits ofnumerous modifications, of which a few are shown in Figs. 5, 6, 7, S,and 9.

Instead of a metallic tube A,provided with insulating-strips B and B, anon-metallic noncombustible tube-such as fireproof tile-pipe A ,Fig.5-may be employed. In these a spiral groove a is cut to receive theresistancecoil 0, which is wound directly upon the material in saidgroove, and the groove afterward filled flush with non-combustiblepowdered or plastic material.

To condense and accelerate the air-current passing through the innertube A, another light tube A, Fig. (3, closed at the bottom and allowingan annular space between the two, may be inserted. An air-current mayalso be caused to pass along the surface of the outer tube D byinclosing it in another light casing A, open at the bottom. In thisconstruction direct radiating will not be obtained.

The heating-surface of the tubes A and D may be increased bycorrugations and projections, and may also be augmented by additionalradiating or air tubes A, inserted or formed between the inner and outertubes A and D, open at top and bottom, as shown in Figs. 7 and S.

In Fig. 9 one of the intermediate coils is provided with a lead c,havinga resistance-coil c, inserted and connected with the main lead by aswitch a", so that a portion of the coils may be cut out and the heatingcapacity thus reduced at will. This may be done with a number of thecoils.

In operation the electric current heats the material 1 on the other,while the latter cond lists the heat generated to the incasing-tubes, orprincipally to one or other of them, if so desired, whence it is takenup by the current of air by radiation.

I claim as my invention- 1. In an electric heater, the combination of atube A, strips of asbestus B, laid upon said tube longitudinally, stripsof mica B, laid upon said asbestus strips, a coil of wire or strip G, ofrefractory metal of low electric conductive power, wound upon saidstrips and its terminals connected with leads, an outer tube D,inclosing said coil and leaving an annular space, a filling of powderednon-combustible non-electric-condnoting material in said annularspace,insulating packing-rings E, closing the ends of said annularspace, covers E, having lugs 6 upon said packing-rings, and bolts E",passing through said lugs and hold ing said covers together,substantially as set forth.

2. In an electric heater, the combination of a tubular core A, insulatedwith strips of asbestus B and mica 13', carrying a coil 0, of wire orstrip of refractory metal of low electric conductive power, an outertube D, inclosing said core and forming an annular space around saidcore and containing insulators through which pass the leads connectingthe terminals of said coil, a powdered nonelectric-conducting materialfilling F in said annular space, insulated covers E, closing saidannular space and held in place by bolts insulating-feetGr on one ofsaid covers, an inner tube A, closed at the bottom, and a casing A"around the external tube D, open at the bottom and forming an annularspace around the same, substantially as set forth.

In testimony whereof I have signed in the presence of the undersignedwitnesses.

THOMAS AHEARN. \Vitnesses:

A. HARVEY, A. TROWSE.

